


Where The Sun Doesn't Shine (You Make Me See Light)

by AceOnIce, PisangGoreng



Category: Shadowhunters (TV)
Genre: Anal Sex, Crack Treated Seriously, Dom Magnus Bane, Dom/sub, Embedded Images, Established Relationship, Fluff and Crack, Fluff and Smut, Gags, Immortal Husbands Magnus Bane/Alec Lightwood, Immortality, M/M, Rimming, Sex Toys, Sub Alec Lightwood, improper use of witchlight, too many tangled references for a smut fic
Language: English
Status: Completed
Published: 2020-12-20
Updated: 2020-12-20
Packaged: 2021-03-10 16:35:13
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,218
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28200246
Author URL: https://archiveofourown.org/users/AceOnIce/pseuds/AceOnIce, https://archiveofourown.org/users/PisangGoreng/pseuds/PisangGoreng
Summary: When Magnus and Alec experiment with the warlock's new witchlight dildo, they both finally see the light (and it's like the fog has lifted).
Relationships: Magnus Bane/Alec Lightwood
Comments: 30
Kudos: 186





	Where The Sun Doesn't Shine (You Make Me See Light)

**Author's Note:**

  * For [PisangGoreng](https://archiveofourown.org/users/PisangGoreng/gifts), [Lalelilolu](https://archiveofourown.org/users/Lalelilolu/gifts), [Xani9](https://archiveofourown.org/users/Xani9/gifts).



> A million thanks to [Spark](https://spark-draws.tumblr.com/) for the lovely artwork that inspired me to finally finish this!! It's so gorgeous!! 
> 
> And of course Xani and Lale have to be mentioned and thanked for encouraging this horribly cursed idea. They're terrible and I love them so much.
> 
> Betad by the wonderful [Lale](https://archiveofourown.org/users/Lalelilolu/pseuds/Lalelilolu) and [Myu](https://archiveofourown.org/users/Myulalie/pseuds/Myulalie). Thank you <3

It’s a seemingly normal night when Magnus snaps a long, black box into existence, only minutes after they finish dinner, and slides it across the kitchen table towards his husband. Alec doesn’t know what to expect, but he reaches for it, raising his eyebrows. 

“You got me something? Did I miss an anniversary?”

Magnus shakes his head, a small smile on his lips. “I was experimenting and it turned out well. I thought it made a lovely gift for you- well, for both of us, really.”

Egged on by his own curiosity, Alec pulls the top off the box, only to pause when he sees what’s inside. It’s a long, crystalline dildo. He glances up at Magnus, “What do you mean you were experimenting?”

“Pick it up,” Magnus encourages, eyes gleaming with a familiar excitement.

Alec picks up the dildo and almost jumps when it lights up, turning a soft blue and white. Witchlight. It’s a dildo made out of witchlight stone. He snorts and looks back up at Magnus, torn between amusement and disbelief. “You made this?”

“I thought you might like it.”

Turning the... _toy_ over in his hands, Alec has to admit, it makes an attractive sight. A bit on the slender side, but long and pretty and entirely unique with its glow, subtle under the brighter kitchen lights. He imagines the way it will shine when Magnus holds it, how it will glow red in the warlock’s hand, a result of his ancestry and his father being a fallen angel. “Is it safe to use?”

“Of course it is, I tested it on myself,” Magnus answers, standing so he can round the table and brush a hand through Alec’s hair, a gentle comfort. “And if you don’t want to use it, I don’t mind a repeat.”

“No.” Alec holds it a little tighter, suddenly feeling possessive of it, aching to have it pressing into him. Imagining Magnus using the toy on himself, bent over his own desk or spread out on their sheets, sweaty and desperate, has Alec half-hard already. He stands up without letting go of the toy and presses a chaste kiss to Magnus’ lips. “I want to try it.”

Magnus’ answering smirk has Alec shivering. “Then let’s move this to the bedroom.”

Alec ends up on his back, naked and tied to the headboard, Magnus between his legs clad in only a pair of white boxers. He's pressing a lubed finger teasingly at Alec's rim, making the shadowhunter squirm against the silky soft sheets, ready for Magnus to just get on with it. “I can’t wait to see you all stretched around this.”

“Can’t do that until you stretch me.”

Magnus slaps his thigh, the impact barely stinging, a warning more than a punishment. “Remember who’s in charge here.”

“Why don’t you show me?” Alec challenges, a teasing smile at his lips, not yet needy enough to obey without hesitation. Magnus raises a brow slightly before snapping his fingers. Suddenly there’s a gag resting in the shadowhunter’s mouth, preventing him from talking. 

“That ought to do,” Magnus says with a small, self-satisfied nod. Alec lets out a sound of complaint, but his erection, curved against his stomach and already leaking, betrays just how much he enjoys being at Magnus’ mercy.

Magnus rubs a finger over his hole again, still teasing more than actually stretching, and Alec huffs. Magnus grins and leans down, licking a stripe across Alec’s rim. Alec lets out a shocked moan at the sudden wet heat.

Magnus takes his time prodding at Alec’s hole, licking him open, fucking Alec with his tongue until Alec is so hard it hurts. Still the warlock continues rimming him, finally sliding a finger in beside his tongue. Alec shudders, gripping at the headboard where his wrists are tied for something to hold to as waves of pleasure roll through him. 

Leaning back, Magnus magicks lube onto his fingers, continuing to slowly open Alec up with one finger, pressing a kiss to the inside of his thigh. “You already look desperate for it, sayang. You’re practically shaking.”

Alec’s response is made incoherent by the gag. Magnus chuckles, sliding in a second finger. “We’ve barely started, don’t tell me I need to activate your stamina rune.” Alec sucks in a breath. The idea is as horrifying as it is appealing. If Magnus activates it, Alec won’t be coming any time soon, but when he does…

“Oh, you like that,” Magnus realizes, eyes glinting. He waves a hand and Alec’s stele appears in his grip. He continues to stretch Alec with his left hand. “What kind of man would I be if I didn’t give my husband what he wants?” Alec’s complaints are lost, stifled by the gag, before they can leave his mouth. 

Magnus leans up over the Nephilim, fingers stilling momentarily, to trace the stamina rune on Alec’s arm. Alec shivers, feeling the cooling angelic magic wash through him. “Perfect.” Magnus tosses Alec’s stele away and it disappears before it can hit the ground. Alec is sure it’s back with the rest of his gear where he’d left it originally.

“Ma-us-”Alec tries to say, but to no avail. 

The warlock hums, renewing his task of opening Alec up. “Patience my love. You know I’ll give you everything you want.”

He can’t argue with that. Magnus has never left him wanting before. So he keeps his complaints to himself- not that he has much choice in the matter given the gag- as Magnus takes his time. 

When Magnus presses his pinky inside of Alec, sliding it in next to his other three fingers, Alec can’t help but imagine taking one more finger, fitting Magnus’ entire fist inside him. The idea has his already aching cock twitching against his stomach. He _needs_ to come but the rune is still active, preventing his orgasm and he sobs around the gag, a tear tracing down his cheek. 

Magnus wipes it away, pausing in his motions and magicking the gag away. “What’s wrong?”

“Nothing,” Alec gasps, swiveling his hips, trying to ride Magnus’ hand. “Feels so good.”

Magnus’ eyes widen in understanding. “ _Oh._ You love being filled like this, don’t you? Love being stuffed.”

Alec lets out a sound that’s half gasp, half sob. Because he _does_ love it. “I need to come.”

“Not yet,” Magnus says with finality, pressing a kiss to Alec’s hip. “You know it will be better if you’re forced to wait.”

He can’t help whining, pressing back against Magnus’ hand, taking him in further. “Please, please, Ma-”

“Hush,” Magnus’ hand snaps against his ass. “Either safeword or shut up. I told you I’ll give you what you want, _when I’m ready.”_

Alec bites his lip, tears still falling down his face. He feels so good it’s painful. 

“There’s my good boy,” Magnus praises, pressing two fingers to Alec’s prostate. Alec keens, shaking through what he’s pretty sure is a dry orgasm. It leaves him panting and unsatisfied, still completely hard. “Did you just-”

“Couldn’t help it,” Alec gasps out.

“I know.” Magnus draws his hand out, lurching up to hover over him, crashing their lips together in a rough kiss that borders on painful. “You’re perfect. I’m going to use the toy now.”

“Yes, yes, _please._ ”

Magnus kisses him once more, quicker this time, before moving back down to kneel between his open legs, reaching for where he’d dropped the witchlight dildo on the comforter. It glows red in his hand and Alec shudders with anticipation. 

Slathering the toy with lube, Magnus grins up at Alec. “I bet you never thought of using a witchlight this way.”

Alec shakes his head, tears momentarily quelled. “No, but I’ll never look at one the same way again.”

“Ready?” Magnus asks, pressing the stone to Alec’s gaping hole. 

“Please,” Alec breathes. The toy is unexpectedly warm, glowing white where it’s touching him. Magnus slowly begins pressing it deeper and they both watch in awe as more and more of the witchlight turns from red to white, casting them both in a dreamlike glow. 

It’s halfway in when it starts to vibrate. Alec jolts, shocked but unbelievably aroused as it presses against his prostate. 

“Well that’s unexpected.”

Alec freezes despite the pleasure coursing through him as the dildo rocks against his prostate. ‘ _Well, that’s unexpected’_ definitely belonged on a list of _things you don’t want to hear about the sex toy that’s already inside of you- especially by the maker of said toy._ “What— Magnus? What’s unexpected?”

“I just didn’t anticipate the… vibrating,” Magnus says calmly, still slowly fucking Alec with the toy. “No matter, it’s not like it’s going to explode.”

Alec’s eyes widen even as a moan escapes him because _fuck_ the toy is warm and vibrating and smooth and perfect. “What?”

“I said it _won’t_ explode,” Magnus presses a kiss to Alec’s inner thigh. 

“That’s not-” the dildo vibrates against his prostate and he lets out a shocked sound of pleasure,”-ah, very comforting.”

Magnus chuckles and moves up the bed to hover over him, still slowly pressing the toy in deeper. “I wouldn’t hurt you- in any way you didn’t want.”

“I know,” Alec breathes, trying to think around the pleasure coursing through him. “I trust you.”

Magnus kisses his cheek, gently. “Let me take care of you.” Alec relaxes back into the mattress, as much as he can with his body taut with arousal. The fear melts away with Magnus leaning over him, protecting him— always. 

“I love you,” Alec gasps as Magnus reaches a hand down to wrap his fingers around Alec’s cock. Magnus smiles softly down at him, glamour falling to reveal his gorgeous cat eyes. The bright light casts shades of white and red over his skin, giving him an odd glow. Alec can’t decide if he looks angelic or beautifully demonic. He doesn’t have the brain power to contemplate it as he throws his head back, letting out a moan, the consistent pressure against his prostate dragging him towards orgasm despite his activated stamina rune.

“I love you too darling,” Magnus says, voice as soft as the light that bathes him in a red glow.

Magnus’ hand tightens around him, stroking with intent, just the way Alec likes. Alec claws at the sheets, his mind going fuzzy with all the sensations washing over him. 

He’s not sure what does it, what finally pushes him over that edge, but he comes with Magnus’ hand around him, the witchlight dildo vibrating against his prostate, the warlock’s name on his lips. As he does, the world seems to explode in an array of bright lights, illuminating the room in rainbows. 

Alec’s runes flare to live, burning bright red sending another jolt of sensation through him, nearly painful with how close he is. Magnus’ eyes glow brighter, magic swirling around him, light blue and glimmering in the rainbow lighting. 

Alec’s chest burns, as if fire is crawling across his skin. Several inches from Alec, harsh blue lines- the same shade as Magnus’ magic- begin tracing themselves into warlock’s chest, forming an unfamiliar symbol

It all happens in a matter of seconds and Alec watches, breathless _,_ barely past his orgasm, as the lights fade, his runes returning to their usual black, Magnus’ magic melting away, the dildo’s vibrations ceasing. All that lingers is the faint pain over his heart, a light ache where the burning has subsided.

Alec is breathing hard as he blinks up at Magnus, glancing between cat eyes and the new mark on the other man’s chest, faded to white now. “What… what just happened?”

“Um…” Magnus looks as confused as Alec feels. He slides the toy out of Alec and sets it, very gently on the bed beside them. “I’m not entirely sure.”

“Magnus—”

Magnus’ fingers trace over Alec’s chest, eyes reverent. “ _This._ I know this rune.”

Alec looks down, at his own chest. The symbol there matches the one on Magnus’ chest perfectly, each stroke identical, the same white color to it. He doesn’t recognize it, knows it isn’t in any official records. And yet, somehow, he also _knows_ it. He tugs at the bindings around his wrists. “Untie me?”

Magnus jolts like he’d forgotten Alec’s hands were tied. He snaps and the rope falls away. Alec sits up, placing a palm to the new rune over Magnus’ chest. It’s warm beneath his palm, even more so than Magnus’ skin. “Forever.”

Magnus nods, blinking rapidly, eyes shiny with unshed tears. 

Alec can’t help grinning and, as he does, a small smile grows on Magnus’ face. The shadowhunter nods towards the toy without taking his eyes off his husband. “I think this was the best idea you’ve ever had.”

“I didn’t know—”

“I know,” Alec breathes, using his free hand to cup Magnus’ face, tracing a thumb under his eye. He knows Magnus would never knowingly make him immortal without asking. Alec presses his forehead to Magnus’. “I want this.”

Magnus lets out a small, disbelieving laugh. His relief is palpable in his breathless, “I love you,” he breathes before crushing their lips together to continue their pre-surprise-immortality activities. After all, Magnus has yet to come and Alec fully intends on rectifying that immediately. The rest of the immortality talks can wait till they’re both sweaty and sated.

**Author's Note:**

> Y'all [Spark](https://spark-draws.tumblr.com/)makes the most lovely artwork (they actually drew a piece for another one of my (less smutty and less cracky fics) and is just a brilliant person so please go check out their tumblr!


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